There has been proposed a vehicle air conditioner that detects a temperature around a passenger in a passenger compartment by the use of an infrared temperature sensor in a non-contact manner and air-conditions the passenger compartment around the passenger automatically on the basis of a temperature detected by the temperature sensor (for example, see Japanese Unexamined Patent Publication No. 2002-172926).
In another vehicle air conditioner, a time constant processing is performed for a temperature detected by an infrared temperature sensor, and air-conditioning of a passenger compartment is performed on the basis of the detected and processed temperature (for example, see Japanese Unexamined Patent Publication No. 2001-347816). To be specific, the air conditioner air-conditions the passenger compartment by the use of the temperature detected a predetermined time before by the infrared temperature sensor. Thus, even if the surface temperature of a temperature detection area by the infrared temperature sensor changes rapidly, the air conditioner prevents the air state in the passenger compartment from being changed in response to a change in the surface temperature.
However, in this kind of vehicle air conditioner, in a case where a high- or low-temperature substance such as flame of tobacco or cooled air of a refrigerator (or cooled canned coffee) comes into the detection area of the infrared temperature sensor (that is, temperature detection area), the air state is not rapidly changed immediately after that time. However, after a predetermined time period, the air state is controlled by the use of the detection temperature showing a high temperature of the tobacco or the like. Thus, after the predetermined time period passes, the air state is abnormally controlled.
Even in a case where the detection surface of the infrared temperature sensor is covered with the passenger's hands, the air state is not rapidly changed immediately after that time. But, after a predetermined time period passes, the air state is controlled abnormally. On the contrary, even if the passenger holds his hands over the detection surface of the infrared temperature sensor for a try, the air state is hardly changed immediately after that time. Hence, this raises also a problem that the passenger may be given feelings of anxiety about whether or not air-conditioning control is really performed under normal operating conditions.
The inventors of the present application have made a study of detecting the surface temperature of a passenger (driver) sitting on the driver's seat by the use of an infrared temperature sensor that is arranged in a dashboard (i.e., instrument board) in the passenger compartment so as to face a driver's seat area. When the infrared temperature sensor is arranged nearer to a steering wheel side than a central portion in the dashboard, an area occupied by the steering wheel becomes larger in a temperature detection area where the infrared temperature sensor can detect temperature. For this reason, areas in which temperature essentially needs to be detected, for example, an area occupied by the driver and having the largest effect on a comfortable feeling, an area occupied by a ceiling and undergoing the effect of radiation from outside the passenger compartment, and an area occupied by side windows and undergoing the effect of outside air temperature and solar radiation amount are reduced. Hence, this causes large detection error in the temperature detected by the infrared temperature sensor. Therefore, it impossible to suitably adjust the air conditioning state in the passenger compartment.